Caitlyn Jenner: 'I spoke to son Brandon first about my transition'

[Caitlyn Jenner} shared her decision to transition - from a man to a woman - with her son Brandon first.

The Olympic star formerly known as Bruce Jenner called eldest son Brandon her "biggest champion". Caitlyn explained she turned to the musician, her son by second wife Linda Thompson, when she finally decided to undergo her life-changing transition last year (15).

In a teaser trailer from show I Am Cait, Caitlyn shares:“The first person I talked to in my family was my son Brandon. Brandon's my little Gandhi in the family. He's a real thinker and has got this great mind.

"I thought Brandon and his wife Leah would be the best ones so we sat down and talked about it."

Caitlyn sought her son out after hearing Brandon say how proud he was of his father. It gave her the confidence to broach the subject with him. "Brandon said to me let's talk about the issue and said, ‘Dad I'm so proud to be your son - every place I go and I hand them my ID they ask if me if my dad is Bruce Jenner,' and he would say 'Yes,' and they'd say, 'We love Bruce'. (He's) very proud."

She adds: "And he said, ‘I haven't been more proud of you than I am right now,' and he was the first one and I felt like 'alright, it's going to be OK'.

"That was wonderful to hear from your son and he is so proud of me now. And that pretty much resonated within the family. Brandon is my biggest champion."

Caitlyn's revelation may come as a surprise to members of his famous Kardashian/Jenner brood as they claim they were not told the news by her.

Khloe Kardashian has said the whole family felt "betrayed" over Caitlyn's transition, after finding out about the former sports star's plans to transition during a meeting with the makers of their TV show, E!.

"They mentioned Bruce had a television show about transitioning, and that's the first we heard of it... We felt betrayed because more business people (knew)," Khloe recalled in an interview with radio show host Howard Stern in January (16).

Khloe and her sisters were left bitterly disappointed

"People would think that we were lying … But no, we believed him," Khloe added to Howard.